1. Field of the Invention
The present invention relates generally to enclosures for receiving and storing digitally coded discs and, more particularly, to an improved engagement means for holding such discs within such enclosures.
2. Description of the Prior Art
Various types of planar discs are in use at the present time to record and store information which is to be retrieved by various means, such as by optical or magnetic means. Typical of such discs are compact discs (CDs) in which information is digitally recorded by use of a laser beam and then read optically by a laser beam. Such discs are used to record audio information, such as musical renditions, video information such as visual images and digital information for use as read only and other memories for use in various applications, such as computer applications. In most instances, at the present time, such discs are sold with information already recorded thereon. In other applications, such discs are sold in blank form and are used by the customer to record information thereon. In the latter case, for example, optical discs are sold for use as computer storage media and are used in hard disc storage systems. In either case, optical imperfections in or on the surfaces of such discs interfere with both the recording and retrieval of information stored on the discs. Care must, therefore, be taken in the storage, moving and handling of such discs to avoid causing any such imperfections.
Compact discs containing laser recorded information are typically packaged in enclosures designed to hold one or more CDs for protecting the discs during storage and shipment. Enclosures commonly used at the present time comprise a three piece assembly consisting of a base or bottom element, an insert or tray in the base/bottom element for positioning and supporting the disc in the base/bottom element, e.g., by a center projection (commonly referred to as a "rosette") which engages the periphery of the aperture in the center of the disc, and a lid or cover which is hinged to the base/bottom element and is closed thereon after the disc is mounted therein on the tray. Other enclosures utilize only two pieces, omit the tray, and position and support the disc via the center projection directly on the base/bottom element. The enclosure is, typically, at least partially transparent and graphics relating to the disc and containing trademark and sales promotional information are usually inserted in such a manner as to be visible through the enclosure.
Most typically, the rosette comprises a raised hub which is formed integrally with the base/bottom element or tray, preferably by injection molding. The hub includes a plurality of small gripping teeth or fingers for radially engaging the central aperture in the CD. Generally, the central aperture of the CD is positioned over the rosette and a slight downward pressure is applied. Due to the relative dimensions of the central aperture and the rosette, the downward pressure causes the gripping teeth or fingers to deflect radially inwardly and to resiliently engage the central aperture of the CD. In this way the rosette engages and secures the CD in place during storage.
It has become conventional for the elements of the CD enclosures to be formed by injection molding. As a consequence the rosettes are formed of the same plastic material as the base or tray with which they are integrally molded. The base and/or tray elements and, therefore, the rosettes have typically been made from pigmented thermoplastic molding resins having sufficient impact resistance to withstand the forces attendant to mounting and unmounting CDs as well as the forces experienced during shipping and handling.
More recently there has arisen a growing demand for additional graphic display space on CD enclosures. As a consequence it has become desirable to provide a clear, see through tray or base so that a larger percentage of graphic area is visible to the consumer. In order to achieve a clear, see through tray or base, a transparent plastic material must be used. One material which has emerged as the material of choice is crystalline polystyrene. Although a functional CD tray or base can be molded with crystalline polystyrene using known injection molding techniques and existing molds without substantial change to the enclosure design, the brittleness of crystalline polystyrene has caused significant problems with the rosette. Specifically, the molded gripping teeth or fingers have evidenced a tendency to fracture and/or break away during mounting and unmounting of the CDs and during shipping and handling operations due to the brittleness of the crystalline polystyrene. This can result in a loss of engagement between the rosette and the central aperture of the CD, allowing the CD to move within the enclosure and to become damaged by impairing the recording media stored thereon. Alternatively, or in addition, the fractured teeth or fingers can become loose and move around in the enclosure, damaging the surface of the CD by scratching the surface and impairing the stored recording media thereon.
Efforts have been made to reinforce the teeth or fingers of the rosette. See, for example, U.S. Pat. No. 5,515,968 and U.S. Pat. No. 5,494,156. However, attempts to redesign the rosettes or to reinforce them suffer from one or more shortcomings which make the resulting rosette either unsatisfactory or not particularly desirable for use in a CD enclosure. Either the rosette is undesirable because it is uneconomical to manufacture or it is unsatisfactory because it remains susceptible to fracture in use and presents substantial risk of damaging the information bearing surface of the disc. Accordingly, there remains a need for a simple, inexpensive to manufacture and easy to use rosette for a CD enclosure which is configured to facilitate safe mounting and unmounting of the disc thereon and which does not present a damage risk for the disc's information bearing surface.